Coil Springs

Jean-Marc Dugas

PCS Member
Before I call the local parts store, what should ask for for the replacement of both front & rear coil springs on my 67 Pontiac Superior?
 
The Pontiac Commercial Chassis used special heavy duty coil springs, and I doubt that you will be able to find anything that closely resembles the spring rate of the originals. Spring rates are determined by the thickness of the wire, and the number of turns in the wire of the spring. GM used different spring rates on each side of the car depending on the equipment that was factory installed, and the type of suspension that was ordered. Although the springs all look the same, when you take the measurements, that is where the difference is. I remember seeing an old movie that was made by Chrysler Corporation showing how springs were made and calculated. An identical spring in physical characteristics, might have as many as 10 different spring rates. Each spring was put into a measuring device, and checked. Then it was put into separate containers depending on its spring rate. They would put different color paint marks on the springs to differentiate between each rating. The spring rate along with the type of shocks determines the ride quality and ride hight of the vehicle.
I went through this very same discussion with another PCS Member a few years ago, but it was after he had replaced all the springs, and the car was actually worse riding with the new springs. He eventually put back the originals, and installed coil over shocks in the rear, and heavy duty gas shocks in the front. That worked out well in the end, and it was also a 1967 Pontiac Commercial Chassis car. If my access on the other site wasn't severely restricted, I could locate the original post for you to read.
 
and the problems will go on. I had this same mess with the Oldsmobile. I tried the heaviest 98 spring I could get and added the coil over shocks. the car drove like pushing an ice cube across the table with your nose. I talked to the people at the armorer spring place and all they said put caddy springs under it. I said BS there not the same. olds has pig tails top and bottom caddy only bottom. we looked around for about a year then went down to the parts store and got a set of CC caddy springs for 89 bucks and shoved them in there. I got my car back. I can now drive it at any speed and it handles correct. the caddy springs are rated at the same GVW as the olds were. the top fits Ok in the pocket, the bottom secured in the mount were it belongs. GM did a lot of this little changes to make the lines different. but most of the parts will interchange between the full size cars. the old trick was to get the 98 OLDS parts and put them on the caddy. they were the same (sometimes) just a tab or bump on the casting different and half again as much money. I can't and won't say they will work in your car. but to have a set made was vary expensive. I found that the front springs off the caddy were about two inches lower the the front of the olds but I gained about two inches in ridding height with the caddy springs. but they tell me 75% of the handling is in the rear. I believe that now. the front and rear GVW rating is on the door tag. get a spring rated that heavy. most of the books list GVW, wire size, coil diameter and over all height. get as close as you can to what you have. as long as they fit the lower mount they "should" work. all I can say is I'm not getting any movement or noise out on the caddy springs under my 98 Olds high top.
 
never thought

Never thought much about springs until I read this. We have a 2 spring shops in town. One actually makes springs...or did. When I was a lot younger some of the car guys would talk about getting their springs 're-arched' to get their cars back to riding the way they thought they should. Of course most of OUR cars were old enough that they had leaf springs. I suppose there is something the shop could do for coils if they had to. It was cheaper than new springs. Don't have any idea how long the re do job would last.
Mike
 
So much for a simple answer such as “ACME coil spring Model P1234” LOL!!!! One thing I have learned over the last couple of years is that there are very few simple answers when dealing with Professional Car restoration.

On that note, would one suggest air bags in the coil springs?

Paul, I will do a search in for posts from you with “springs” as subject in the professionalcar.org archives to see what I can find. If I do I’ll copy the pertinent information here.
 
I looked through my notes on my Chrysler, and found this company that came highly recommended by another old car guy. They can supply you with both coil and leaf springs. Not cheap, but what is today? The good news, is that they are close to Canada, but not knowing what part of Canada you live in, it might still be a long drive....

http://www.eatonsprings.com
Eaton Detroit Spring Company
1555 Michigan
Detroit, MI 48216
313-963-3839
sales@eatonsprings.com
 
I've heard that Eaton Spring was great. Wait - I think I heard that from you, Paul. Interesting topic. I've wondered the same about my mild ambulance conversion, whether or not they used the wagon torsion bars and rear leaf springs, or if they were upgraded by the coach manufacturer. For shocks up front, the consensus among the Forward Look people is that a paticular KYB shock works great up-front. But that's mor MoPar talk; not GM.
 
check this people out http://www.coilsprings.com/limo/index.html
if i remember right they were the ones that i talked to the tech support people on and they told me use the caddy springs. they came to be able to make you any spring you need send you old one in and they will match it. don't have a clue how much that would be as we did not get past the use the caddy springs.
 
What have you decided to do for replacing the springs? The suspense is killing us... :rolleyes:
 
Be careful if you choose the airbag angle! Those things can't be NEAR anything that'll even come close to touching them or it'll rub through. I have a friend that bagged his 1962 Impala & one of his bags blew as a result of something slightly rubbing the bag @ ride height... and that thing dropped like a lead potato. Yeah this was a streetmachine application but wanted to throw out a word of caution to you. To get you by, put on a pair of air shocks & play with the air pressure to get the height & feel you like.
 
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